Spring, particularly for use in percussion-tools



M. L. BRAMSON.

SPRING, PARTICULARLY FOR USE IN PERCUSSION TOOLS.

APPLICATION FILED NOV-2, 1920.

Patented Dec. 13, 1921.

. UNETFD STATES ATENT orricn.

MOGENS LOUIS BRAMS ON, 0F STAFFORD, ENGLAND.

SPRING, PARTICULARLY FOR USE IN PERCUSSION-TOOLS.

Specification of Letters latent.

Application filed November 2, 1920. Serial No. 421,405. 7

2, 1920; Norway Sept. 30, 1920; Spain Oct.v

5, 1920; Sweden Oct. 1,1920) of which the following is a specification.

This invention relates to resonators. In many instances and particularlyin the case of percussion tools it is necessary to suspend areciprocating mass between springs so arranged and adjusted that acondition of resonance is established between the mass and the springs.v q

Hitherto this has been effected by suspending the mass between metalsprings of suitable form but it has been found that in percussion toolsfor instance, where the mass is subjected to a high rate ofreciprocation the springs frequently break.

vVe have proved by experience that it is possible to substitute forthese metallic sprin s, e ther springs formed or constituted by liquidcolumns or capacities and the desired resonance conditions can beobtained by adjusting the respective areas upon which theliquid'operates, and the volumes of the capacities or springs to. fulfilthe conditions requisite for a resonator.

The underlying principle of the present invention is the substitutionforthe metallic springs hitherto employed, liquid springs, and theinvention consists broadly in suspending the reciprocating mass betweencolumns of liquid.

It follows that the invention depends for its success upon the fact thatliquidsare not incompressible but elastic.

Although capable of application to other uses where it is required toprovide a spring suspension for a reciprocating mass the invention isparticularly applicable to percussion tools for use in wave transmissionsystems, the general principles of which are now well known and areoutlined in the specification of Letters Patent No. 9029 of 1913.

In carrying the invention into practice,

three fundamental conditions must be ob served: Firstly, there must beresonance be-.

tween the reciprocating mass and the capacities. That is to say, thereciprocating mass and the capacities must be in a state of resonanceand satisfy the equation L0a =1 when Lzco-etlicient of inertia, Cco-efli- Patented Dee.13, 1921.

cient of capacity and a the angular ve l locity in radians per second.Secondly, the

mean pressure in the linemust be balancedby the maximum pressure on thefront capacity acting on their respective areas.

This second condition is only strictly true in cases where there isnoinitial pressure inv the system but where there is an initial pressure,.as is usually the case in practice,

this initial pressure has to be taken into account and it is a moreaccurate statement for all conditions to say that the force exerted bythe mean pressure in the line acting on its area of the reciprocatingmass plus the force exerted by the minimum pressure in the rear capacityacting on its area of the reciprocating mass must equal the force ex!erted by the maximum pressure 1n the front. capacity acting 011 its areaof the IeClPI'OCELlE ing mass. I v

Thlrdly, the mean pressure in the line and the pressures in the twocapacities must all be equal when the apparatus is in operation.'

The first and second of these conditions is in accordance with the sameprlnciples as when metallic springs are used, and are obtained in thesame way. The third condition is necessary because leakage will, in anycase, make the mean pressures equalandtherefore ifthey are not equalwhen the appa ratus is working, it will cease to work when they are.

In the accompanying drawing vice illustrating my inventiondiagrammatically. q

Fig. 2 is a longitudinal diagrammatic sec tion illustrating theapplication of this invention to a riveting hammer.

Referring to the drawings 66 the reciprocating mass, 6 designates thei11- let or line connection from a wave transmission generator, 6 is thearea of the reciprocating mass (1 upon which the pressure in the lineoperates, 0 is the front capacity, the annulus c is the area upon whichthe pressure in this front capacity acts, d is the rear capacity and theannulus d is the area designates x Figure 1 is a longitudinal section ofa de pacity acts.

' is .57 of the force exerted by the maximum mean value.

1n the forward direction into the front capressure in'the frontcapacity0 acting on the annulus 0 The operation may be stated in popularlanguage follows :The pressure waves enter at the inlet or lineconnection 2) and the pressure rises and falls from zero to maximum inaccordance with a given frequency in the manner now well known. The blowcommences to be struck, or, in other words,

the energy commences to be imparted when the reciprocat'ed mass atreaches its foremost positionindicated in the diagram by the dottedline. This occurs when the pressure in the line b has risen from Zero toits mean pressure. This blow continues, or mother words, the energycontinues to be imparted until the pressure in the line b has risen toits maximum value and fallen again to its The movement of the mass apacity c has caused the pressure in the caparit c to rise owing to thefact that there is no displacement of theliquid, and when the linepressure falls to its mean value the pressure in the capacity 0 actingon the annulus c exerts a force which just balances the opposing forceexerted by the mean pressure in the line b acting on the area Z2 plusthe force exerted by the pressure in the rear capacity cl acting on theannulus.

Assuming that there is no initial pressure in the system there will benopr'essure in the capacity (Z at this instant but assuming that thereis 'an initial pressure in the system the pressure in the capacity (Zwill be this initial pressure only, '5; e. the pressure in the capaci'ty(i will be at its minimum value.

Immediately the line pressure at'b falls below its mean value it followsthat the force exertk'a'd upon the reciprocating mass in It will beunderstood that the above represents the action of one period in thewave and the action is repeated with the wave frequency. That is to say,assuming a wave frequency of 2,300 periods per minute, which is a usualfrequency, the action will be repeated 2,300 times per minute. Theappli-,

erating as springs so arranged and adjusted that'a condition ofresonance is established between the mass'and the liquid springssubstantially as specified.

2. A resonator comprising a reciprocating mass having an area subject tothe pressure of a liquid column in one direction and an area subject tothe pressure of a liquid column in the opposite direction the respectiveareas and pressures being so related that a condition of resonance isestablished between the mass and the liquid columns which opcrate assprings substantially as specified.

8. A percussion device comprising a reciprocating mass adaptedperiodically to impart energy at one position and to have en ergyperiodically imparted to it at another position,'and liquid capacitiesbetween which the mass 1s suspended the arrangement belng such that therec1prooat1ng mass and the springs constituted by the liquid columns arein resonance substantially as specified.

4. A wave transmission percussion device 7 comprising a reciprocatingmass adapted periodicallyto impart energy at one posltion and to besubject to the alternating'pressure of a wave transmission generator atanother posltion, and a front capacity and a rear ca pacity betweenwhich the mass is mounted in spring suspension so that the mass and thesprings constituted by the capacities are in resonance substantially asspecified.

Signed at London, England, this twentieth day of October, 1920.

MOGENS LOUIS BRAlWSON.

